This invention relates to a process of presulfuration of a hydrocarbon processing catalyst. The invention is an improvement of the process described in patent EP-B-153233 of the applicant.
It is often desirable to proceed to a sulfuration (generally called "presulfuration") of metals entering the composition of certain catalysts for refining and/or hydroconversion of hydrocarbons either when these catalysts are new or at the end of the regeneration of these catalysts before reusing them.
A presulfuration of the new or regenerated catalysts is thus desirable for the use of these catalysts in the refining reactions, for example, the reactions of desulfuration or hydrodesulfuration of various gasolines, for example, gasolines of catalytic cracking or steam cracking whose sulfur content it is suitable to lower, before use, without modifying the octane number of these gasolines or by modifying it as little as possible.
The catalyst used for this type of desulfuration or hydrodesulfuration contains a generally nonacid support, for example, an alumina or alumina mixtures (U.S. Pat. No. 4 334 982) or any other suitable support with a base of at least one oxide of a metal, e.g., magnesia or metalloid (U.S. Pat. Nos. 4,132,632, 4,140,626), silica, silica-aluminas, silica-magnesias, fluorosilicas, boron aluminas, clays, carbons, fluroaluminas), this mixture or these mixtures of supports able to be at least partly in amorphous form or in crystallized form (zeolites) and the catalyst further containing 0.2 to 30% of at least one active metal of groups VI, VIII or the like selected, for example, from the group consisting of cobalt, molybdenum, nickel and tungsten (U.S. Pat. No. 3,732,155 and 3,804,748).
A sulfuration or presulfuration of regenerated catalyst is also desirable in the reactions of hydrocarbon hydroreforming (reforming in particular of a naphtha) and of aromatic hydrocarbon production ("aromizing"), for example, the production of benzene, toluene and xylenes (ortho, meta or para), either from gasolines that are unsaturated or unsaturated (for example, gasolines of pyrolysis, cracking, in particular steam cracking, or catalytic reforming), or else from naphthenic hydrocarbons capable of being transformed into aromatic hydrocarbons by dehydrogenation.
The catalyst can contain, for example, at least one metal of the family of platinum, i.e., a noble metal such as platinum, palladium, iridium, rhodium, ruthenium, osmium deposited on a suitable support (alumina, silica, silica-alumina, fluoroaluminas, flurosilicas, zeolite, etc... or mixtures of such supports).
A sulfuration (presulfuration) of a new or regenerated catalyst is also suitable, in some cases, for the partial or total catalyst sulfuration, also with a base of one of the supports already cited at least one of the active metals already cited, usable in reactions, hydrocarbon conversions such as the reactions of hydrogenation, dehydrogenation, alkylation, hydroalkylation, dealkylation, hydrodealkylation, steam dealkylation, isomerization and hydrodemetalization of the heavy batches.
The metals of catalysts used in refining, hydrorefining or petrochemistry, whether they are new or regenerated, are most often in oxidized form, at times in metal form (for some metals of reforming catalysts, in particular). Now, the metals of these catalysts, often being active only in sulfur form or at least partially sulfur form, it is therefore necessary for the refiner or the petrochemist to perform a sulfuration of the catalyst before its use.
The regeneration of the catalysts is now performed increasingly by a specialist of catalyst regeneration, at times far from the industrial unit. Now, it seems reasonable to think of restoring to the refiner a product ready for use, which makes possible the original and efficient process of the applicant described in EP.B.153233.
When the catalyst is to be subjected, from its start preferably on the site ("in situ"), to the standard activation reaction in the presence of hydrogen (generally above 100.degree. C.), this process makes it possible then to proceed, thanks to the presence of hydrogen on the site, to the sulfuration at required rates, stoichiometric or nonstoichiometric, of the active metal or metals entering the composition of the catalyst. The process consists in incorporating ammonium sulfide in the absence of hydrogen in the porosity of the new or regenerated catalyst.
In this process, the catalyst is generally impregnated "ex situ" in the absence of hydrogen with an aqueous ammonium sulfide solution (NH.sub.4).sub.2 at a temperature between 0.degree. and 50.degree. C., preferably between 10.degree. to 35.degree. C. and, for example, at room temperature to incorporate the suitable degree of sulfur in the porosity of the catalyst, the processing of the catalyst then being followed by a drying of this catalyst, for example, at a temperature lower than 120.degree. C. and preferably between 95.degree. and 115.degree. C. Above 120.degree. C., it has been seen that the sulfur was partially eliminated from the catalyst.
One of the advantages of the process is to be able to proceed to the presulfuration of the catalyst only in the presence of an aqueous solution. It has been proposed by the applicant in U.S. Pat. No. 4,719,195 to introduce organic polysulfides in the porosity of the catalytic batch; now, this last method presents the drawback of performing the presulfuration in the presence of an organic solvent of "white spirit" type that is more difficult to eliminate than the water at the end of the process. This process further presents the advantage of being able to use the commercial ammonium sulfide solution just as it is.